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Train to Gain: Heart Health

Stroke of bad luck. Could low cholesterol (yes, low) contribute to strokes in healthy exercising people?

Medical texts list two basic types of strokes. In one, a blood vessel spontaneously bursts, and the resulting blood leakage in the skull can lead to brain damage or death. The other type of stroke is caused by a thrombus, or blood clot, that travels to the brain and blocks an artery.

The primary risk factor for both types of strokes is hypertension, or high blood pressure. Both weight training and aerobic exercise help lower blood pressure while keeping arteries flexible and better able to withstand the stress that can lead to a stroke.

While it’s rare to see a young, healthy person with no apparent cardiovascular risk factors suffer a stroke, it does sometimes happen. The use of certain types of birth control pills can increase the risk of clot formations in the brain. The other type of stroke, termed an intracerebral hemorrhage (ICH), is very rare in healthy, fit people. In fact, when it does happen, doctors are often at a loss to identify it.

A new study describes two causes of ICH in previously healthy, active and fit people who engaged in regular exercise.1 The first case involved a 26-year-old man who regularly lifted weights. He sometimes drank alcohol but didn’t smoke. On the day he suffered his stroke, he had returned to the gym from a one-month layoff. He trained his upper body using weights estimated at 60 percent of his maximum so as not to tax himself too much after the layoff.

Despite that precaution, he felt a headache halfway through the workout and felt ‘vaguely unwell.’ When he tried to open his locker, he had trouble remembering the combination and dialing it with his right hand. Now certain that something was wrong, he called a friend and noticed that his speech was slurred. He had the friend take him to a hospital, where an ICH was diagnosed. Tests revealed that he showed none of the usual causes of that type of stroke, such as a congenital malformation of brain blood vessels.

The other case featured a 50-year-old gym teacher who was also a competitive triathlete. He trained mainly with endurance exercise five to six days a week. He had no history of high blood pressure and didn’t drink alcohol or smoke. On the day of his stroke he had just completed a light workout, then collapsed into unconsciousness. As in the previous case, he was treated by removal of the blood seepage forming in his brain as a result of the stroke.

These cases are interesting because neither man showed any of the usual risk factors for the type of stroke they suffered, such as atherosclerosis, blood vessel malformations in the brain, brain tumors or aneurysms (weakness in an arterial wall that makes it prone to bursting). So how did they get the strokes?

It’s possible that the man lifting weights was holding his breath while training (Valsalva maneuver), which is known to increase arterial blood pressure. He may have had a small, undetected aneurysm that burst. Or he may have had an embolus, or circulating blood clot, that blocked a small artery in the brain, causing the artery to leak blood.

Interestingly, that type of stroke is also related to low blood cholesterol levels. Lower readings are usually desirable, but readings below 160 may predispose some people to a stroke. Cholesterol is a building block of cell membranes that form the inner walls of arteries, and a relative deficiency of cholesterol may lead to weaker arteries. While that may sound far-fetched, studies involving stroke-prone rats show that increasing their cholesterol levels reduces stroke incidence. Research shows that the two most common risk factors for ICH in younger persons are low cholesterol levels (35 percent) and hypertension (13 percent).

Additional risk factors for stroke in otherwise healthy, fit people include the presence of a type of body protein called apolipoprotein E, which is also related to the onset of Alzheimer’s disease. Taking substances known to raise blood pressure, such as phenylpropanolamine (PPA), in doses of 75 milligrams or more a day, can precipitate a stroke in some people, particularly when taken with other pressor (blood-pressure-increasing) substances, such as caffeine. Similarly, anyone with a family history of strokes should be careful about using ephedrine or mahuang supplements, which slightly raise blood pressure. The same goes for alcohol of any kind.

‘Jerry Brainum

1 Cayen, B., et al. (2002). Intracerebral hemorrhage in previously healthy adults following aerobic and anaerobic exercise. Brain Injury. 16:397-405.

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